JP2963385B2 - Two-shaft gas turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-shaft gas turbine, and more particularly to an improvement in the sealing performance between a turbine rotor and a nozzle.

[0002]

2. Description of the Related Art As shown in FIG. 4, a gas generator 2 which comprises a compressor, a combustor and a turbine for driving a compressor and generates a high-temperature and high-pressure gas, and an energy of the high-temperature and high-pressure gas. In a two-shaft gas turbine comprising an output turbine 16 which is taken out as power, the gas generator 2
The rotating shaft of the power turbine 16 and the output shaft 17 of the output turbine 16 are usually coaxial (located on the same axis) (Japanese Patent Application Laid-Open No. 2-268835).
Reference). The flow path 14 for guiding the flow from the gas generator 2 to the output turbine 16 is also cylindrical or conical in shape, like the gas generator 2 and the output turbine 16, and is therefore in the intermediate duct 15 forming the flow path 14. Is also axisymmetric, the deformation does not adversely affect the deformation of the gas generator 2 or the output turbine 16.

On the other hand, the direction of the output shaft of such a coaxial two-shaft gas turbine and the direction of the input shaft of driven equipment such as a generator and a compressor have a certain angle or are orthogonal. In the case of the output shaft standing type two-shaft gas turbine, a bevel gear for separately changing the rotating shaft direction from the output shaft direction of the output turbine to the input shaft direction of the driven device is required. Also,
The installation space for these components must be large.

As a means for improving this situation, the output shaft direction of the output turbine is changed in the gas turbine with respect to the rotation axis direction of the gas generator so that the output shaft is coaxial or parallel to the input shaft direction of the driven equipment. It is possible to arrange. This eliminates the need for a device, such as a bevel gear, for changing the rotation direction, and also achieves a significant reduction in installation space.

[0005]

However, in the case of the above-described two-shaft gas turbine of the output shaft type, the intermediate duct for guiding the working gas from the gas generator to the output turbine turns the working gas to output. In order to be directed to the turbine, a complicated shape of a scroll type or a spiral type which is not axisymmetric is obtained. Therefore, high-temperature and high-pressure working gas locally deforms unevenly, and in particular, deforms the output turbine casing. As a result, between the turbine rotor and the nozzle (static vane) fixed to the casing. There is a problem that misalignment easily occurs in the provided labyrinth seal.

On the other hand, in the labyrinth seal portion between the turbine rotor and the nozzle, when the gap is made as small as possible, the leakage from the seal portion is reduced, and the efficiency of the output turbine can be improved. If the misalignment is large, it is difficult to reduce the gap. When the gap is set to be equal to or less than the relative displacement during operation of the turbine rotor and the nozzle, the two contact with each other at the seal portion,
There is a possibility that the seal portion may be damaged or vibration due to contact may be induced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-shaft gas turbine capable of solving the above-mentioned problems and improving the sealing performance between a turbine rotor and a nozzle and improving turbine efficiency.

[0008]

According to one aspect of the present invention, there is provided a compressor, a combustor and a turbine for driving a compressor for generating a high-temperature, high-pressure working gas. a gas generator, the rotation axis and the rotation axis inclined or perpendicular to the axis of rotation of the gas generator
An output turbine having a supported turbine rotor and taking out the energy of the working gas as power, and operating gas from the gas generator to the output turbine in a first stage from a bearing housing side housing the bearing. A two-shaft gas turbine which is introduced into a turbine rotor via a nozzle, wherein the concentricity is maintained between the bearing housing and a first-stage nozzle of an output turbine while allowing relative displacement between the two in the axial direction. And concentric holding means for causing the concentricity.

With the above arrangement, the working gas from the gas generator, the power turbine, the bearing housing side which houses the bearing of its through the first stage nozzle is introduced into the turbine rotor, concentric holding means, Concentricity is maintained between the bearing housing and the first stage nozzle of the power turbine while allowing relative displacement in the axial direction between the two. Therefore, the concentricity is maintained between the turbine rotor and the nozzle supported by the bearing housing, and the radial gap between the two becomes uniform on the circumference. Therefore, the gap therebetween can be reduced and the sealing performance can be improved. .

That is, in the conventional coaxial two-shaft gas turbine, as shown in FIG. 4, the bearing box 40 of the output turbine 16 and the nozzle 24 having the labyrinth seal 28 on the inner peripheral portion are formed by a rotor disk. Although it was difficult to provide a concentric holding mechanism between the two, the present invention, in the present invention, in a vertical two-shaft gas turbine, a bearing box of the output turbine is connected between the gas generator and the output turbine. By providing the gas near the intermediate duct, the working gas flows from the bearing housing side to the turbine rotor, so that the bearing housing and the first stage nozzle of the output turbine are structurally close to each other. Therefore, by providing a concentric holding structure between them, the concentricity between the turbine rotor supported by the bearing housing and the inner peripheral portion of the first stage nozzle provided with the labyrinth seal can always be ensured, and even with a small rabbi ring seal gap. The possibility of causing damage to the seal portion due to the contact of the seal portion can be eliminated.

According to one embodiment of the present invention, the concentric holding means is a ring-shaped diaphragm connecting the first stage nozzle and the bearing housing. Since the ring-shaped diaphragm thermally expands uniformly in the radial direction, there is no contact between the turbine rotor supported by the bearing housing and the first-stage nozzle due to misalignment. Can be improved.

Preferably, a labyrinth seal is provided between the inner peripheral surface of the first stage nozzle and the turbine rotor,
An outer peripheral portion of the diaphragm is fixed to a nozzle side surface located radially outward of a labyrinth seal in the first stage nozzle.

According to another embodiment of the present invention, the concentric holding means is a spline provided on the first stage nozzle and the bearing box and meshing with each other. Therefore, there is no contact between the turbine rotor and the nozzle supported by the bearing housing due to misalignment.
Sealability can be improved.

Preferably, a labyrinth seal is provided between the inner peripheral surface of the first stage nozzle and the turbine rotor,
Further, the spline is formed on the inner peripheral surface of the first stage nozzle.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a side view of a two-shaft gas turbine according to one embodiment of the present invention. The output-shaft type two-shaft gas turbine 1 includes a gas generator 2 for generating a high-temperature, high-pressure working gas G and a bearing box in which a working gas from the gas generator 2 is housed in a bearing 9 of an output turbine 6. An output turbine 6 having an intermediate duct 4 introduced into the output turbine 6 from the side 10 and a rotating shaft 8 orthogonal to the rotating shaft of the gas generator 2 and extracting the energy of the working gas G from the intermediate duct 4 as power. And The intermediate duct 4 has an annular scroll flow path 2 surrounding the rotation shaft 8 of the output turbine 6.
The flow of the working gas along the rotation axis of the gas generator 2 is turned by the scroll flow path 26 in the direction along the rotation axis 8 of the output turbine 6. An exhaust duct (not shown) is connected to an upper portion of the output turbine 6.
The gas generator 2 includes a compressor (not shown) that compresses air, a combustor that mixes fuel into the compressed air and burns, and a compressor driving turbine that is driven by combustion gas from the combustor to drive the compressor. Consists of A driven device such as a generator is coaxially connected to a lower portion of the rotating shaft 8 of the output turbine 6.

In the output turbine 6, a turbine rotor 22 having moving blades is supported by a bearing box 10 via a bearing 9 of a rotary shaft 8, and further supported by a base K via the bearing box 10. . The casing 18 is supported on the base K at a plurality of locations on the outer periphery via support legs F, and a nozzle (stationary vane) 24 facing the turbine rotor 22 is fixed inside. The intermediate duct 4 is supported by the base K via support legs at a plurality of locations (not shown). The intermediate duct 4 has a double structure including an inner duct 50 and an outer duct 52. The inner duct 50 made of a thin plate is fixed to the first stage nozzle 24a, and the thick outer duct 52 is made of metal. Casing 1 via an expansion joint 56 made of bellows made of
8 or the first stage nozzle 24a.

As shown in FIG. 2, a labyrinth seal 28 is provided between the turbine rotor 22 and the nozzle 24.
A labyrinth seal 29 is also provided between the upper part of the bearing housing 10 and the rotating shaft 8. In addition, this gas turbine 1
Is the first stage nozzle 24a of the bearing housing 10 and the power turbine 6.
And a concentric holding means 30 such as a ring-shaped diaphragm that maintains concentricity while allowing relative displacement in the axial direction between the two. This diaphragm 3
0 indicates that the outer peripheral portion of the diaphragm 30 is
a is fixed to the side surface of the first stage nozzle 24a located radially outward of the labyrinth seal 28 provided between the inner peripheral surface of the first stage nozzle a and the turbine rotor 22 by a fastening means such as a bolt.

That is, in the conventional coaxial two-shaft gas turbine, the bearing box 40 of the output turbine 16 shown in FIG. 4 and the nozzle 24 having the labyrinth seal 28 on the inner peripheral portion are formed by:
Although it was difficult to directly provide a concentric holding mechanism between the two because the rotor disk 22 was sandwiched therebetween, in the present invention, the bearing box 10 containing the bearing 9 of the output turbine 6 of FIG. The first stage nozzle 24a of the bearing box 10 and the output turbine 6 is provided by providing the working gas G from the bearing box 10 side to the turbine rotor 22 by providing the working gas G from the bearing box 10 side to the turbine rotor 22. Closed structurally. Therefore, the concentric holding means 3 of FIG.
0, the first stage nozzle 2 having the bearing box 10 for supporting the turbine rotor 22 and the labyrinth seal 28
The concentricity with the inner peripheral portion of the seal 4a can always be ensured, and even a small gap in the labyrinth seal 28 can eliminate the possibility of damage or vibration of the seal due to the contact of the seal.

The operation of the two-shaft gas turbine will be described below. The high-temperature and high-pressure working gas G generated in the gas generator 2 in FIG. 1 is ejected in the horizontal direction, and flows into the scroll flow path 26 via the intermediate duct 4. The working gas G that has flowed into the scroll flow path 26 spreads annularly around the rotation shaft 8 of the output turbine 6 along the scroll flow path 26, and is output while flowing along the inner peripheral surface shape in the scroll flow path 26. The flow direction is turned toward the rotating shaft 8 of the turbine 6, and is jetted from the outlet toward the cascade of the output turbine 6. The output turbine 6 is turned to drive the rotating shaft 8. Driven equipment such as a generator is driven by the rotation of the rotating shaft 8.

Since the intermediate duct 4 is not an axially symmetric shape but a scroll-shaped complicated shape, it receives local pressure and heat of the working gas G and causes local non-uniform deformation. This deformation is absorbed to some extent by the expansion joint 56,
Nevertheless, a deforming force that causes misalignment with the turbine rotor 22 is applied to the casing 18 of the output turbine 6. In contrast, in this embodiment, the diaphragm 30
Thereby, the turbine rotor 22 supported by the bearing housing 10 and the first stage nozzle 24a of the output turbine 6 are connected and kept concentric, so that there is no misalignment between the two. Therefore, the clearance between the labyrinth seals 28 can be reduced, and the sealing performance can be improved. This improves turbine efficiency. In addition, since the diaphragm 30 is deformed in the axial direction, it absorbs the axial displacement between the bearing housing 10 and the first stage nozzle 24a mainly caused by thermal expansion.

FIG. 3 shows another embodiment. In the figure, the concentric holding means comprises a first stage nozzle 24a and a bearing box 10
And are formed by splines 32 meshing with each other. In this case, the first stage nozzle 2 shown in FIG.
A labyrinth seal 28 is provided between the inner peripheral surface of the turbine rotor 4a and the turbine rotor 22.
In FIG. 3B which is a cross-sectional view of FIG.
The spline 32 is formed on the inner peripheral surface of 4a.
As a result, the turbine rotor 2 supported by the bearing housing 10
Since the misalignment does not occur between the second stage nozzle 24a and the first stage nozzle 24a, the gap of the labyrinth seal 28 can be reduced, and the sealing performance can be improved. The spline 3
2 and the upper part of the bearing housing 10 and the first stage nozzle 24a
Even if a circumferential surface that fits with a small gap with the inner peripheral portion of the rim is formed, the concentricity of the two can be maintained to some extent.

In the above embodiments, the rotation axes of the gas generator 2 and the output turbine 6 are orthogonal to each other, but may be inclined at a predetermined angle.

[0023]

According to the present invention, the concentric holding means maintains concentricity between the bearing housing and the first stage nozzle of the power turbine while allowing relative displacement between them in the axial direction.
Therefore, the concentricity is maintained between the turbine rotor and the nozzle supported by the bearing housing, and the radial gap between the two is uniform on the circumference. Therefore, the gap between the two is reduced to improve the sealing performance. Can be.

[Brief description of the drawings]

FIG. 1 is a side view showing a two-shaft gas turbine according to one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3A is a side view showing another embodiment, and FIG. 3B is a sectional view of the same.

FIG. 4 is a side view showing a conventional two-shaft gas turbine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Two-shaft gas turbine, 2 ... Gas generator, 6 ... Output turbine, 10 ... Bearing housing, 22 ... Turbine rotor, 24a
... First-stage nozzle, 28... Labyrinth seal, 30.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-296456 (JP, A) JP-A-3-164534 (JP, A) JP-A-2-67044 (JP, U) 14051 (JP, B1) US Patent 3,358,440 (US, A)

Claims (5)

(57) [Claims] 1. A gas generator comprising a compressor, a combustor, and a turbine for driving a compressor, for generating a high-temperature, high-pressure working gas, and a rotating shaft inclined or orthogonal to a rotating shaft of the gas generator. And the tar supported by this rotating shaft
An output turbine that has a bin rotor and takes out the energy of the working gas as power. The working gas from the gas generator is supplied to the output turbine from a bearing housing side housing the bearing via a first stage nozzle. A two-shaft gas turbine introduced to a rotor, wherein concentric holding means for maintaining concentricity between the bearing housing and a first stage nozzle of an output turbine while allowing relative displacement in the axial direction between the two. A two-shaft gas turbine comprising: 2. The two-shaft gas turbine according to claim 1, wherein the concentric holding means is a ring-shaped diaphragm connecting the first stage nozzle and the bearing housing. 3. The labyrinth seal according to claim 2, wherein a labyrinth seal is provided between an inner peripheral surface of the first stage nozzle and a turbine rotor, and an outer peripheral portion of the diaphragm has a diameter larger than that of the labyrinth seal in the first stage nozzle. A two-shaft gas turbine fixed to the side of the nozzle located outward in the direction. 4. The two-shaft gas turbine according to claim 1, wherein the concentric holding means is a spline provided on the first stage nozzle and the bearing box and meshing with each other. 5. The labyrinth seal according to claim 4, wherein a labyrinth seal is provided between an inner peripheral surface of the first stage nozzle and a turbine rotor, and the spline is formed on an inner peripheral surface of the first stage nozzle. Two-shaft gas turbine.